File: issue-112048-unsizing-niche.rs

package info (click to toggle)
rustc 1.85.0%2Bdfsg3-1
  • links: PTS, VCS
  • area: main
  • in suites: experimental, sid, trixie
  • size: 893,396 kB
  • sloc: xml: 158,127; python: 35,830; javascript: 19,497; cpp: 19,002; sh: 17,245; ansic: 13,127; asm: 4,376; makefile: 1,051; perl: 29; lisp: 29; ruby: 19; sql: 11
file content (29 lines) | stat: -rw-r--r-- 508 bytes parent folder | download | duplicates (5)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
//@ run-pass

// Check that unsizing does not change which field is considered for niche layout.

#![allow(dead_code)]

#[derive(Clone)]
struct WideptrField<T: ?Sized> {
    first: usize,
    second: usize,
    niche: NicheAtEnd,
    tail: T,
}

#[derive(Clone)]
#[repr(C)]
struct NicheAtEnd {
    arr: [u8; 7],
    b: bool,
}

type Tail = [bool; 8];

fn main() {
    assert_eq!(
        core::mem::offset_of!(WideptrField<Tail>, niche),
        core::mem::offset_of!(WideptrField<dyn Send>, niche)
    );
}